The Flow Cytometry Core Facility (FCCP) provides state-of-the-art flow cytometry services to researchers at the Cancer Center. Extensive user support is provided, consisting of daily instrument startup, maintenance and quality control; easy and reliable online scheduling systems; extensive training options; a site license for FlowJo analysis software; one-on-one consultations between individual researchers and Core Facility staff. These services include Operator-Assisted analysis on FACSCalibur and CyAn, Operator-Assisted cell sorting on two Aria and two MoFlo cell sorters, as well as User-Operated analysis on FACSCalibur, LSR II and Fortessa and User-Operated cell sorting on two Aria cell sorters. The combination of equipment and user support offers researchers opportunity to integrate flow cytometric analysis and cell sorting into their research projects. FCCP provides easy access to purified cell populations and to analysis of cellular subsets and processes, essential elements of many modern cell biology research projects. The presence of FCCP therefore plays an important role in the Center's capability to increase our knowledge of the processes that give rise to cancer, and to improve cancer diagnosis and therapy. The services and collaborative work provided by the FCCF has supported the research of 111 investigators in the past year. During the past grant period the work of the Core has contributed to 450 publications of researchers from 8 research programs. For example, the Flow Core was essential in helping the Rudensky lab demonstrate that regulatory T(Treg) cells integrate environmental cues that suppress particular types of Inflammation. These studies showed that Treg cell-mediated suppression of Th17-driven pathology is facilitated by activation of STAT3 downstream of interleukin 10-R (IL-1 OR) engagement of interleukin 10 (IL-10). This study demonstrated that IL-10 endows Treg cells with the ability to suppress pathogenic Thi7 cell responses. For these studies the Core provided expert flow analysis of STAT3 staining and cell sorting of Fox3-YFPT+ and Fox3-TFP- cells.